,&3 



LIBRARY OF CONGRESS 



012 822 384 8 * 




UNITED STATES DEPARTMENT OF AGRICULTURE 

| BULLETIN No. 781 

Contribution from the States Relations Service 
A. C. TRUE, Director 




jS^fr'^WU 




Washington, D. C. 



PROFESSIONAL PAPER 



May 31, 1919 



DIGESTIBILITY OF SOME BY-PRODUCT OILS/ 

By Arthub D. Holmes, Specialist in Charge of Digestion Experiments, 

Office of Home Economics. 



CONTENTS. 



Page. 

Introduction 1 

Previous investigations 1 

Possible recovery and use of by- 
product oils 2 

Digestion experiments with men 3 

Apricot-kernel oil 4 



Page. 

Cherry-kernel oil 6 

Melon-seed oil i_ 8 

Peach-kernel oil 10 

Pumpkin-seed oil 12 

Tomato-seed oil 14 

Discussion 15 



INTRODUCTION. 

In planning the experiments to determine the digestibility of 
edible fats it was early recognized that in order to be of greatest 
value the experiments with the different fats should be conducted 
under as nearly as possible identical conditions. Accordingly, the 
same experimental methods have been used throughout a series with 
40 or more edible fats to which the present study is the most recent 
contribution. These methods were quite fully discussed in the 
initial report of this series. 2 As a result of this uniformity of method, 
the value reported for the digestibility of any individual fat dis- 
cussed is directly comparable with the figures obtained for the 

others. 

PREVIOUS INVESTIGATIONS. 

Papers have appeared from time to time, reporting the digesti- 
bility of such animal fats 3 as lard ; beef fat ; mutton fat (kidney fat) ; 
butter; cream; chicken, goose, brisket, egg-yolk, and fish fats; goat's 

1 Prepared under the direction of C. F. Langworthy, Chief, Office of Home Economics. 

2 U. S. Dept. Agr. Bui. 310 (1915). 

3 U. S. Dept. Agr. Buls. 310 (1915), 507 (1917). 

Note. — This bulletin records studies of the digestibility of apricot-kernel oil, cherry- 
kernel oil, melon-seed oil, peach-kernel oil, punipkin-seed oil, and tomato-seed oil. It is 
. primarily of interest to students and investigators of food problems. 
106003°— Bull. 781—19 1 



•V 



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2 BULLETIN 781, U. S. DEPARTMENT OF AGRICULTURE. '\ ' >-\ - 



A? v 



butter; kid, hard-palate, and horse fats; oleo oil and oleo stearin; 
ox-marrow, ox-tail, and turtle fats. Other papers have reported the 
digestibility of a large number of vegetable fats, 1 including olive, 
cottonseed, peanut, coconut, and sesame oils; cocoa butter; and al- 
mond, black-walnut, Brazil-nut, butternut, English- walnut, hickory- 
nut, pecan, corn, soy-bean, sunflower-seed, Japanese mustard-seed, 
rapeseed, and charlock-seed oils. The oils of such nuts as almond, 
black and English walnuts, Brazil nuts, and pecan are ordinarily 
consumed as constituents of the nuts in which they naturally occur, 
but with these exceptions practically all of the oils studied are com- 
monly separated from the materials in which they naturally occur 
before being used for table or culinary purposes. 

POSSIBLE RECOVERY AND USE OF BY-PRODUCT OILS. 

As a result of the enormously increased demand for fats and oils 
for both technical and edible purposes it has seemed desirable to 
make a study of the nature and value of fixed oils present in seeds 
and nuts not hitherto grown or utilized for the production of oil. 
For some time studies have been carried on by the Department of 
Agriculture to ascertain the commercial possibilities of recovering 
the fixed oils contained in many of the pits and seeds occurring as by- 
products of the fruit canning and drying industries. In 1908 Eabak 2 
reported studies on the chemical and physical characteristics and the 
commercial uses and value of the fixed and volatile oils which may be 
obtained from the peach, apricot, and prune kernels. He estimates 
that from 210 to 420 tons of peach-kernel oil (fixed oil) and from 350 
to 400 tons of apricot oil may be obtained from the by-product peach 
and apricot kernels produced in California alone. He also estimates 
that the amount of raisin-seed oil capable of being manufactured 
from waste raisin seed would be from 348 to 464 tons yearly. 3 He 
states 4 that the possible commercial utilization of the waste cherry 
pits of a normal year's output should yield 134 tons of fixed oil. In 
a recent paper the same author 5 states that the quantity of oil capa- 
ble of being extracted from tomato seeds occurring as a by-product of 
tomatoes used for pulping purposes (catsups, etc.) would be about 
343 tons annually. 

From these findings it is apparent that the quantity of oil obtain- 
able from the pits and seeds occurring as by-products is not small. 
In order to make the recovery of these oils a practical proposition 
even in those localities where the pits and seeds are to be had in suffi- 

1 U. S. Dept. Agr. Bills. 505 (1917), 630 (1918), 687 (1918). 
2 U. S. Dept. Agr. Bur. Plant Indus. Bui. 133 (1908), pp. 34. 
3 U. S. Dept. Agr. Bur. riant Indus. Bui. 276 (1913), p. 30. 
*U. S. Dept. Agr. Bui. 350 (1916), p. 16. 
B U. S. Dept. Agr. Bui. 632 (1917), p. 9. 

o." •*. i*. 

JUL 2-"l919 



PIGESTIBILITY OF SOME BY-PRODUCT OILS. 3 

cient quantities to obviate long hauls it apparently was necessary to 
find some use for the entire pit. 

The residue, commercially known as press cake, remaining after 
the expression of oil from peach, apricot, and cherry kernels, has 
much the same composition and nutritive value for stock feeding as 
the press cakes obtained from such oil seeds as soy bean, linseed, 
peanut, coconut, and cotton seed. Until very recently, however, the 
outer woody portion of the pits seemed to be of little value except 
for fuel purposes. Experimental tests and large-scale use of the 
carbon produced from the woody portion of fruit pits showed quite 
conclusively that this carbon is valuable, especially for the manu- 
facture of gas masks. Thus, with a possible commercial demand 
existing for all portions of the fruit pits, it seemed desirable to give 
consideration to the utilization of these by-products. 

While the oils obtainable from waste pits and seeds are satisfactory 
for a variety of technical purposes, it is of course evident that if they 
can be commercially prepared so that they are satisfactory for such 
purposes they should be available for food. Especially is this true at 
the present when a world-wide shortage of fats and oils exists. Ac- 
cordingly, laboratory studies of the expression of oils from various 
kernels were made. The results of these studies showed that if care 
was observed both in the preparation of the pits and in the expression 
of oil from them a high-grade edible oil could be obtained. 

If the peach, apricot, and cherry pits were allowed to stand for 
any length of time in the moist condition in which they were re- 
moved from the fruits, fermentation developed and the oil which 
was obtained was usually not suited for edible purposes. On the 
other hand, it was found in laboratory procedure that if the peach, 
apricot, and cherry kernels were dried, ground, and expressed by 
hydraulic pressure (i. e., "cold pressed"), the oils obtained were 
perfectly satisfactory for table purposes without any refining other 
than merely filtering. The peach, apricot, and cherry oils prepared 
in this laboratory by the above procedure were of a bland flavor, and 
when mixed with, vinegar and condiments made excellent French 
dressing. In view of these findings it was decided to determine how 
well these oils are tolerated by the human body and to what extent 
they are digested. Accordingly, a supply of a number of oils which 
may be obtained from the by-products of the canning industry was 
secured, and the coefficients of digestibility were determined in the 
same manner as those of the other edible oils reported in previous 
publications. 

DIGESTION EXPERIMENTS WITH MEN. 

The subjects who assisted with this investigation were men in good 
health, whose ages ranged from 20 to 40 years. In order that the 



4 BULLETIN 781, U. S. DEPARTMENT OF AGRICULTURE. 

squad should represent an average group of persons of these ages 
an attempt was made to secure individuals who should represent both 
the active and athletic type of person and the less active type em- 
ployed at a sedentary occupation. The subjects were all students 
with sufficient understanding of nutrition and physiology to appre- 
ciate the necessity for strict adherence to the directions given them. 
At the same time they were not informed as to the specific purpose of 
the experiments in which they were participating. 

In the case of the oils here discussed the quantities available for 
experimental purposes were insufficient to permit as large a number 
of tests as it has been the policy to make in such investigations. Ac- 
cordingly, only four tests were made with apricot-kernel oil. four 
with cherry-kernel oil, three with melon-seed oil, three with peach- 
kernel oil, two with pumpkin-seed oil, and three with tomato-seed oil. 

The test periods were of the customary three-day or nine-meal 
duration, and sufficient time elapsed between test periods so that the 
diets did not become too monotonous. During the periods which in- 
tervened between test periods the subjects secured their meals at their 
boarding places, and were thus afforded considerable variety in their 
diet. No record was made of body weight, but accurate weighings 
were made of the food served, the uneaten portion of food, and the 
feces resulting from the test diet. Both food and feces were analyzed 
to determine the percentages of protein, fat, and carbohydrate 
digested. 

The individual oil under consideration was fed in a special corn- 
starch blancmange flavored with caramel and vanilla to mask the 
nature of the oil present. This blancmange was served in conjunction 
with a diet containing a minimum of fat and consisting of wheat 
biscuit, oranges, and sugar. 

APRICOT-KERNEL OIL. 

Apricot oil, like many other oils obtainable from the pits of fruits, 
has been used little if at all in this country for edibile purposes. A 
study reported by Eabak x of the commercial possibilities of apricot- 
kernel oil indicates that the chemical and physical properties of this 
oil are quite similar to those of the more widely used oils, such as 
cottonseed, peanut, coconut, corn, and soy-bean oils. Tests of the 
digestibility of apricot oil seemed especially desirable, as no informa- 
tion regarding it was found in literature. 

The apricot oil studied in this investigation was obtained by cold 
pressing dried apricot kernels secured through the courtesy of M. E. 
Jaffa, of the University of California. The oil so obtained was of 
light-yellow color and free from any marked odor or taste. It pos- 

HJ. S. Dept. Agr. Bur. riant Indus. Bui. 133 (1908), pp. 34. 



DIGESTIBILITY OF SOME BY-PRODUCT OILS. 



sessed the essential characteristics of a salad oil and mixed with 
vinegar formed a very agreeable salad dressing. In order that the 
coefficient of digestibility obtained should be directly comparable 
with those for other fats in this series, the apricot oil here used was 
incorporated in a blancmange rather than used in the form of a salad 
dressing ; but there is no reason to suppose that the difference in the 
manner of use would make any appreciable difference in the di- 
gestibility. 

The following tables contain the essential data for interpreting the 
results of the digestion experiments with apricot oil : 

Data of digestion experiments with apricot oil in a simple mixed diet. 





Weight 
of food. 


Constituents of foods. 


Experiment, subject, and diet. 


Water. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


Experiment No. 559, subject H. R. G.: 

Blancmange containing apricot oil 

Wheat biscuit 


Grams. 

1,443.0 
369.0 
442.0 


Grams. 

664.5 

33.2 

384.1 


Grams. 

24.4 

39.1 

3.5 


Grams. 

155.3 

5.5 

.9 


Grams. 

588.0 

285.3 

51.3 


Grams. 

10.8 

5 9 


Fruit 


2 2 




















Total food consumed 


2,254.0 
82.0 


1,081.8 


67.0 
24.1 


161.7 
8.5 


924.6 
43.5 


18 9 


Feces ' 


5 9 














42.9 
64.0 


153.2 
94.7 

99.7 


881.1 
95.3 


13.0 


Digestibility of entire ration (per cent) . . 






68.8 


Estimated digestibility of oil alone (per 




















Experiment No. 560, subject A. J. H.: 
Blancmange containing apricot oil. 
Wheat biscuit - - 


1,748.0 

18.0 

103.0 

32.0 


805.0 

1.6 

89.5 


29.5 
1.9 

.8 


188.1 
.3 
.2 


712.3 
13.9 

12.0 
32.0 


13.1 
.3 


Fruit 


.5 


Sugar 














Total food consumed 


1,901.0 
79.0 


896.1 


32.2 
27.3 


188.6 
14.6 


770.2 
29.8 


13 9 


Feces 


7.3 








Amount utilized 






4.9 
15.2 


174.0 
92.3 

96.4 


740.4 
96.1 


6.6 


Digestibility of entire ration (per cent). . 






47.5 


Estimated digestibility of oil alone (per 




















Experiment No. 561, subject P. K.: 

Wheat biscuit . 


2, 133. 
371.0 
714.0 
111.0 


982.3 

33.4 

620.5 


36.0 

39.3 

5.7 


229.5 
5.6 
1.4 


869.2 

2S6.8 

82.8 

111.0 


16.0 
5.9 


Fruit 


3.6 


Sugar 














Total food consumed 


3,329.0 
77.0 


1,636.2 


81.0 
26.3 


236.5 
10.9 


1,349.8 
33.6 


25.5 




6.2 








Amount utilized 






54.7 
67.5 


225.6 
95.4 

98.6 


1,316.2 
97.5 


19.3 


Digestibility of entire ration (per cent) . . 






75.7 


Estimated digestibility of oil alone (per 
cent) 




















Experiment No. 562, subject C J. W.: 

Blancmange containing apricot oil 

Wheat biscuit 


2,224.0 

429.0 

937.0 

72.0 


1,024.1 

38.6 

814.2 


37.6 

45.5 

7.5 


239.3 
6.4 
1.9 


906.3 

331.6 

108.7 

72.0 


16.7 
6.9 


Fruit 


4.7 


Sugar „ 














Total food consumed 


3, 662. 
95.0 


1, 876. 9 


90.6 
30.5 


247.6 
12.2 


1,418.6 
45.3 


28.3 


Feces 


7.0 














60.1 
66.3 


235.4 
95.1 

98.8 
69.5 


1,373.3 
96.8 


21.3 


Digestibility of entire ration (per cent) . . 






75.3 


Estimated digestibility of oil alone (per 








Average food consumed per subject per day.. 


928.8 


457.6 


22.6 


371.9 


7.2 



6 BULLETIN" 781, U. S. DEPARTMENT OF AGRICULTURE. 

Summary of digestion experiments with apricot oil in a simple mixed diet. 





Experiment No. 


Subject. 


Digestibility of entire ration. 


Estimated 
digestibil- 




Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


ity of apri- 
cot oil 
alone. 


559 


H. R. G 


Per cent. 
64.0 
15.2 
67.5 
66.3 


Per cent. 
94.7 
92.3 
95.4 
95.1 


Per cent. 
95.3 
96.1 
97.5 
96.8 


Per cent. 
68.8 
47.5 
75.7 
75.3 


Per cent. 
99.7 


560 


A. J.H 


96.4 


561 


P. K 


98.6 


562 


C.J. W 


98.8 




Average 








53.3 


94.4 


96.4 


66.8 


98.4 











The coefficients of digestibility of the diet as a whole are compar- 
able to those obtained in other tests with edible oils, being 53.3 per 
cent for protein, 94.4 per cent for fat, and 96.4 per cent for carbohy- 
drate. On an average the subjects ate 23 grams of protein, 70 grams 
of fat, and 372 grams of carbohydrate daily, which had an energy 
value of 2,200 calories. The figure obtained for the digestibility of 
apricot oil alone, 98.4 per cent, indicates that this oil possesses a high 
nutritive value. In the tests referred to above, none of the subjects 
reported any unusual physiological conditions resulting from the in- 
gestion of apricot oil. The results of these experiments as a whole, 
therefore, would seem to indicate that ^a high-grade cold-pressed 
apricot oil may be freely and safely used for edible purposes. 

CHERRY-KERNEL OIL. 

When cherry kernels are subjected to pressure and " cold pressed " a 
light-yellow, 'bland, fatty oil is obtained. Lewkowitsch * reports that 
in South Germany cold-pressed cherry-kernel oil is used for edible 
purposes. He further says that the oil expressed at higher tempera- 
ture is used for soap making and illuminating purposes, but that 
cherry oil is not used as an adulterant of almond oil because of its 
tendency to become rancid. 

In discussing the value and uses of cherry-kernel oil for other than 
edible purposes, Eabak 2 states that since this oil closely resembles 
almond, peach, and apricot oil it should be well adapted for use in 
pharmaceutical preparations. 

The cherry-kernel oil studied in the experiments here reported was 
obtained by expression from dried cherry pits which were secured 
through the courtesy of a large canning establishment. The kernels 
were removed from the cherry pits by passing the pits through a 
mill having vertical grinding plates so set as to crack the pits without 
crushing the kernels. (The cracked pits were separated from the 



1 Chemical Technology and Analysis of Oils, Fats, and Waxes. 
& Co. (Ltd.), 1909, vol. 2, p. 225. 

a U. S. Dept. Agr. Bui. 350 (191G), pp. 8, 17. 



Loudon : Macmillan 



DIGESTIBILITY OF SOME BY-PRODUCT OILS. 7 

kernels, without crushing them, by mechanical means and finally by 
hand picking.) The cleaned, thoroughly dried kernels were ground 
(using the fine knife) with an ordinary household meat chopper. 
The oil was expressed from the finely cut kernels by means of a 
laboratory press which developed a pressure of approximately 2,700 
pounds per square inch and which was secured for the purpose from 
the Drug Plant and Poisonous Plant Laboratories of the Bureau of 
Plant Industry. The oil which was obtained in this manner was free 
from sediment, of a light-yellow color, and possessed a bland, fatty 
taste. When a sample mixed with vinegar and condiments was pre- 
pared as a French dressing, its origin could not be detected by those 
unaware of its source, though all agreed that the dressing was unusu- 
ally appetizing. 

The cherry-kernel oil was thoroughly mixed and incorporated in 
the usual cornstarch blancmange. The essential data resulting from 
the tests made with this oil are reported in the tables which follow : 

Data of digestion experiments, ivith cherry-kernel oil in a simple mixed diet. 





Weight 
of food. 


Constituents of foods. 


Experiment, subject, and diet. 


Water. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


Experiment No. 673, subject A. A. F.: 

Blancmange containing cherry-kernel 
oil 


Grams. 

1,681.0 
345.0 
850.0 
179.0 


Grams. 

780.0 
31.0 

738.7 


Grams. 

59.8 

36.6 

6.8 


Grams. 

157.0 

5.2 

1.7 


Grams. 

669.2 

266.7 

98.6 

179.0 


Grams. 
15.0 


Wheat biscuit 


5.5 


Fruit 


4.2 


Sugar 














Total food consumed 


3,055.0 
65.0 


1,549.7 


103.2 
18.0 


163.9 
10.6 


1,213.5 
27.6 


24.7 


Feces 


8.8 














85.2 
82.6 


153.3 
93.5 

97.3 


1, 185. 9 
97.7 


15.9 


Digestibility of entire ration (per cent) . . 






64.4 


Estimated digestibility of oil alone (per 




















Experiment No. 674. subject P. K.: 

Blancmange containing cherry-kernel 
oil 


2,366.0 
304.0 
403.0 
148.0 


1,097.8 

27.4 

350.2 


84.2 

32.2 

3.2 


221.0 
4.5 

.8 


941.9 

235.0 

46.8 

148.0 


21.1 


Wheat biscuit 


4.9 


Fruit 


2.0 


Sugar 














Total food consumed 


3,221.0 
66.0 


1,475.4 


119. 6. 
20.5 


226.3 
10.2 


1,371.7 
30.0 


28.0 


Feces 


5.3 














99.1 
• 82.9 


216.1 
95.5 
98.3 


1,341.7 
97.8 


22.7 


Digestibility of entire ration (per cent) . 






81.1 


Estimated digestibility of oil alone (per cent) 


















Experiment No. 675, subject J. C M.: 

Blancmange containing cherry-kernel 
oil 


2,149.0 
282.0 
635.0 
192.0 


997.2 

25.4 

551.8 


76.5 

29.9 

5.1 


200.7 
4.2 
1.3 


855.5 

218.0 

73.6 

192.0 


19.1 


Wheat biscuit 


4.5 


Fruit 


3.2 


Sugar. 














Total food consumed 


3,258.0 
76.0 


1,574.4 


111.5 
22.8 


200.8 
9.9 


1,339.1 
35.9 


26.8 


Feces 


7.4 








Amount utilized 






88.7 
79.6 


196.3 
95.2 
98.8 


1,303.2 
97.3 


19.4 


Digestibility of entire ration (per cent) . . 






72.4 


"RRtim a ted digestibility "f "il alrme 





















8 



BULLETIN 781, U. S. DEPARTMENT OF AGRICULTURE. 



Data of digestion experiments with cherry-kernel oil in a simple mixed diet — 

Continued. 





Weight 
of food. 


Constituents of foods. 


Experiment, subject, and diet. 


Water. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


Experiment No. 676, subject A. A. R.: 

Blancmange containing cherry-kernel 
oil 


Grams. 
1, 166. 

178.0 
1,263.0 

131.0 


Grams. 

541.0 

16.0 

1,097.6 


Grams. 
41.5 
18.9 
10.1 


Grams. 

108.9 

2.7 

2.5 


Grams. 
464.2 
137.6 
146.5 
131.0 


Grams. 
10.4 


Wheat biscuit 


2.8 


Fruit 


6.3 


Sugar 














Total food consumed 


2,738.0 
53.0 


1,654.6 


70.5 
18.1 


114. 1 
7.9 


879.3 
21.2 


19.5 


Feces 


5.8 








Amount utilized 






52.4 
74.3 


106.2 
93.0 

97.4 
59.2 


858.1 
97.6 


13.7 


Digestibility of entire ration (per cent). . 






70.3 


Estimated digestibility of oil alone (per 
cent 








Average food consumed per subject per day.. 


1,022.7 


521.2 


33.7 


400.3 


S3 



Summary of digestion experiments with cherry-kernel oil in a simple mixed diet. 





Experiment No. 


Subject. 


Digestibility of entire ration. 


Estimated 
digesti- 




Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


bility of 
cherry- 
kernel 

oil alone. 


673 ..'. 


A. A. F 

P. K 


Per cent. 
82.6 
82.9 
79.6 
74.3 


Per cent. 
93.5 
95.5 
95.2 
93.0 


Per cent. 
97.7 
97.8 
97.3 
97.6 


Per cent. 
64.4 
81.1 
72.4 
70.3 


Per cent. 
97.3 


674 


98.3 


675 


J. CM 


98.8 


676 


A. A. It 


97.4 




Average 








79.9 


94.3 


97.6 


72.1 


98.0 











It will be noted from the above data that the diet as a whole was 
quite well digested, the values obtained being 79.9 per cent for pro- 
tein, 94.3 per cent for fat, and 97.6 per cent for carbohydrate. On an 
average the subjects ate 34 grams of protein, 59 grams of fat, and 400 
grams of carbohydrate, which supplied 2,270 calories of energy. No 
attempt was made to ascertain how much cherry-kernel oil could be 
eaten daily without producing a laxative effect ; but, since one of the 
subjects ate aproximately 74 grams daily for the three-day period, it 
seems apparent that the limit of tolerance for this oil is in excess of 
this amount. 

The high digestibility of cherry-kernel oil, 98 per cent, when con- 
sidered in connection with the pleasing appearance and flavor of the 
cold-pressed oil, warrants the belief that when cherry pits are ob- 
tainable in quantity they should prove a valuable source of a high- 
grade culinary or table oil. 

MELON-SEED OIL. 

While melon (cantaloup) seeds are not available in this country 
in sufficient quantities to be of commercial importance as a source of 



DIGESTIBILITY OF SOME BY-PRODUCT OILS. 9 

oil, Lewkowitsch reports 1 that melon seeds form an article of com- 
merce on the Slave Coast and Gold Coast of West Africa. In studies 
of the relative commercial value of unutilized oil-producing seeds 
and nuts as possible sources of oil, H. S. Bailey, oil specialist of the 
Bureau of Chemistry, gave some attention to this oil. A sample of 
cantaloup-seed oil was expressed from cleaned, dried cantaloup seed 
in a continuous-process-expeller type of oil press under conditions 
approximating those of the commercial oil mill. The cold-pressed oil 
which was obtained was of a light-yellow color without characteristic 
odor or flavor. Since this oil seemed to possess the desirable char- 
acteristics of a table oil, it was decided to determine its digestibility, 
and accordingly three tests were made, the results of which are re- 
ported in the following table : 

Data of digestion experiments icith cantaloup-seed oil in a simple mixed diet. 





• 

Weight 

of 

food. 


Constituents of foods. 


Experiment, subject, and diet. 


Water. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


Experiment No. 891, subject G. S. M.: 

Blancmange containing cantaloup-seed 
oil 


■Grams. 

1, 057. 

120.0 

1, 153. 

293.0 


Grams. 

495.8 

10.8 

1, 002. 


Grams. 

18.6 

12.7 

9.2 


Grams. 

124.4 

1.8 

2.3 


Grams. 

409.8 

92.8 

133; 7 

293.0 


Grams. 

8.4 


Wheat biscuit 


1.9 


Fruit 


5 8 


Sugar 














Total food consumed 


2, 623. 
39.0 


1, 508. 6 


40.5 
10.3 


128.5 
2.9 


929.3 
23.5 


16.1 


Feces '. 


2.3 








Amount utilized 






30. 2 
74.6 


125.6 
97.7 

100.0 


905.8 
97.5 


13.8 


Digestibility of entire ration (per cent) . . 






85.7 


Estimated digestibility of oil alone (per 
cent) .• 




















Experiment No. 892, subject M. L. M.: 
Blancmange containing cantaloup-seed 
oil 


862.0 
231.0 
932.0 
150.0 


404.4 

20.8 

809.9 


15.2 

24.5 

7.5 


101.4 
3.5 

1.9 


334.2 

178.5 
108.1 
150.0 


6.8 


Wheat biscuit 


3.7 


Fruit 


4.6 


Sugar 














Total food consumed 


. 2, 175. 
37.0 


1,235.1 


47.2 
11.6 


106.8 
5.9 


770.8 
15.2 


15.1 


Feces 


4.3 








Amount utilized 






35.6 
75.4 


100.9 
94.5 

97.8 


755.6 
98.0 


10.8 


Digestibility of entire ration (per cent) . . 






71.5 


Estimated digestibility of oil alone (per 
cent) 




















Experiment No. 893, subject W. O'C: 

Blancmange containing cantaloup-seed 
oil 


1, 092. 
179.0 

1,221.0 
528.0 


512.3 

16.1 

1,061.1 


19.2 

19.0 

9.8 


128.5 
2.7 
2.4 


423.4 
138.4 
141.6 
528.0 


8.6 


Wheat biscuit 


2.8 


Fruit 


6.1 


Sugar : 














Total food consumed 


3, 020. 
63.0 


1, 589. 5 


48.0 
16.1 


133.6 
10.5 


1,231.4 
30.6 


17.5 


Feces 


5.8 














31.9 
66.5 


123.1 
92.1 

96.7 
41.0 


1,200.8 
97.5 


11.7 


Digestibility of entire ration (per cent) . . 






66.9 


Estimated digestibility of oil alone (per 








Average food consumed per subject per day. . 


868.7 


481.5 


15.1 


325.7 


5.4 



1 Chemical Technology and Analysis of Oils, Fats, and Waxes. London: Macmillan & Co. (Ltd.), 
1909, vol. 2, p. 127. 



10 



BULLETIN 781, U. S. DEPARTMENT OF AGRICULTURE. 



Summary of digestion experiments with cantaloup-seed oil in a simple mixed 

diet. 





Experiment No. 


Subject. 


Digestibility of entire ration. 


Estimated 
digesti- 
bility of 

cantaloup- 
seed oil 
alone. 




Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


891 


G. S. M 


Per cent. 
74.6 
75.4 
66.5 


Per cent. 
97.7 
94.5 
92.1 


Per cent. 
97.5 
98.0 
97.5 


Per cent. 
85.7 
71.5 
66.9 


Per cent. 
100.0 


892 


M. L. M 


97.8 


893 


W. O'C. 


96.7 




Average 








72.2 


94.8 


97.7 


74.7 


98.2 











The value 98.2 per cent obtained for the digestibility of the can- 
taloup-seed oil alone indicates that this oil is very completely di- 
gested. An average of 15 grams of protein, 41 grams of fat, and 
326 grams of carbohydrate, which supplied 1,730 calories, was eaten 
per man daily, of which 72 per cent df the protein, 95 per cent of the 
fat, and 98 per cent of the carbohydrate was digested, showing that 
the cantaloup-seed oil did not exert any unfavorable influence on the 
digestibility of the diet as a whole. The cantaloup-seed-oil blanc- 
mange was as palatable as the similar dishes prepared with other 
oils. It should be noted, however, that because of the limited amount 
of cantaloup-seed oil available for experimental purposes, the actual 
amount of blancmange eaten daily by the subjects was considerably 
less than in most of the experiments reported in this investigation. 

The experiments here reported may, nevertheless, be considered as 
evidence that good quality cold-pressed cantaloup-seed oil is very 
satisfactory for edible purposes. 

PEACH-KERNEL OIL. 

The peach-kernel oil which was studied in the experiments reported 
below was expressed under laboratory conditions. A liberal supply 
of peach stones was obtained from a large eastern fruit-canning 
establishment. The peach stones were shipped as soon as removed 
from the fruit, in the moist condition, and when they arrived at the 
laboratory they had commenced to ferment. The stones were imme- 
diately cracked by hand and the kernels carefully separated. These 
were slowly but thoroughly dried, after which they were finely 
ground with an ordinary meat chopper. The ground kernels were 
subjected to hydraulic pressure and an oil of a clear pale-yellow 
color with an agreeable nutlike taste, resembling in physical appear- 
ance highly refined cottonseed oil, was obtained. The oil was prac- 
tically free from sediment and received no treatment, other than 
filtering, before it was used. 



DIGESTIBILITY OF SOME BY-PRODUCT OILS. 



11 



Since the amount of peach-kernel oil available for experimental 
purposes was limited, only three tests with this oil were completed. 
The results which were obtained in these tests are included in the 
tables below : 



Data of digestion experiments ivitli peach-kernel oil in a simple mixed diet. 





Weight 
of food. 


Constituents of foods. 


Experiment, subject, and diet. 


Water. 


Protein. 


Fat. 


Carbohy- 
drates. 


Ash. 


Experiment No. 724, subject P. K.: 

Blancmange containing peach-kernel oil. 
Wheat biscuit 


Grams. 

1, 751. 
278.0 
500.0 
172.0 


Grams. 

757.0 

25.0 

434.5 


Grams. 

67.6 

29.5 

4.0 


Grams. 

219.4 

4.2 

1.0 


Grams. 

693.9 

214.9 

58.0 

172.0 


Grams. 

13.1 

4.4 


Fruit 


2.5 


Sugar 














Total food consumed 


2,701.0 
82.0 


1,216.5 


101.1 
8.6 


224.6 
17.9 


1, 138. 8 
48.6 


20 




6.9 














92.5 
91.5 


206.7 
92.0 

95.5 


1, 090. 2 
95.7 


13.1 


Digestibility of entire ration (per cent) . . 






65.5 


Estimated digestibility of oil alone (per 
cent) 




















Experiment No. 725, subject J. C. M.: 

Blancmange containing peach-kernel oil. 
Wheat biscuit 


1,743.0 
431.0 

1, 177. 
140.0 


753.5 

38.8 

1,022.8 


67.3 

45.7 

9.4 


218.4 
6.4 
2.4 


690.7 
333.2 
136.5 
140.0 


13.1 
6.9 


Fruit 


5.9 
















Total food consumed 


3,491.0 
89.0 


1,815.1 


122.4 

7.8 


227.2 
8.0 


1,300.4 

65.8 


25.9 




7.4 








Amount utilized 






114.6 
93.6 


219.2 
96.5 

100.0 


1,234.6 
94.9 


IS. 5 


Digestibility of entire ration (per cent) . . 






71.4 


Estimated digestibility of oil alone (per 
cent) , 




















Experiment No. 726, subject A. A. R.: 

Blancmange containing peach-kernel oil . 
Wheat biscuit 


800.0 

391.0 

1,253.0 

175.0 


345. 9 

35.2 

1, 088. 9 


30.9 
41.4 
10.0 


100.2 

• 5.9 

2.5 


317.0 
302.2 
145.3 
175.0 


6.0 
6.3 


Fruit 


6.3 


Sugar 














Total food consumed 


2, 619. 
85.0 


1,470.0 


82.3 
28.0 


108.6 
14.1 


939.5 
33.5 


18.6 


Feces 


9.4 








Amount utilized 






54.3 
66.0 


94.5 
87.0 

94.3 
62.3 


906.0 
96.4 


9.2 


Digestibility of entire ration (per cent) . . 






49.5 


Estimated digestibility of oil alone (pei 
cent) ." 








Average food consumed per subject per day. 


979.0 


500.2 


34.0 


375.4 


7.2 



Summary of digestion experiments with peach-kernel oil in a simple mixed diet. 





Experiment No. 


Subject. 


Digestibility of entire ration. 


Estimated 
digesti- 




Protein. 


Fat. 


Carbohy- 
drate. 


Ash. 


bility of 
peach- 
kernel oil 
alone. 


724 


P. K 


Per cent. 
91.5 
93.6 
66.0 


Per cent. 
92.0 
96.5 
87.0 


Per cent. 
95.7 
94.9 
96.4 


Per cent. 
65.5 
71.4 
49.5 


Per cent. 
95.5 


725 


J. C. M 


100.0 


726 


A. A. R 


94.3 




Average 








83.7 


91.8 


95.7 


62.1 


96.6 











12 BULLETIN 781, U. S. DEPARTMENT OF AGRICULTURE. 

The results of three tests with peach-kernel oil show that the diet 
as a whole was well assimilated, the digestibility of the different 
constituents being 83.7 per cent for protein, 91.8 per cent for fat, 
and 95.7 per cent for carbohydrate. An average of 31 grams of pro- 
tein, 62 grams of fat, and 375 grams of carbohydrate, which supplied 
2,200 calories, was eaten per man daily. The subjects all reported 
that they felt in normal physical condition throughout the test period, 
which indicated that peach-kernel oil when included as a part of 
a simple mixed diet was well tolerated. The digestibility of peach- 
kernel oil alone, 96.6 per cent, may be considered as evidence that 
this oil is very well assimilated and would prove a valuable food oil. 

PUMPKIN-SEED OIL. 

The oil that is obtained by cold expression of pumpkin seeds is 
classified as a semidrying oil and is of a slightly greenish-yellow 
color. In South Russia this oil is prepared on a commercial scale 
by roasting the pumpkin seeds, after which the oil is hot pressed. 
Lewkowitsch * states that the hot-pressed oil is viscous, of a brownish- 
green color by transmitted light, and of a deep red color by reflected 
light. He further states that attempts to bleach and refine hot- 
pressed pumpkin-seed oil have not met with success. 

While the amount of pumpkin canned at present is not large, both 
the output of the individual factories and the number of canneries 
packing pumpkin are increasing and the indications are that eventu- 
ally the available supply of pumpkin seed will be sufficient to war- 
rant commercial consideration. 

The pumpkin-seed oil studied in the tests here reported was ob- 
tained through the courtesy of H. S. Bailey, of the Bureau of 
Chemistry. It was prepared by cold pressing a supply of pumpkin 
seeds obtained from a commercial canning establishment. It may be 
assumed that this oil was very nearly representative of high-grade 
pumpkin-seed oil of commerce. Since only a very limited supply 
of pumpkin-seed oil was available, only two tests were possible. The 
results which were obtained in these tests are reported in the tables 
following : 

1 Chemical Technology and Analysis of Oils, Fats, and Waxes. London : Macmillan 
' & Co. (Ltd.), 1909, vol. 2, p. 124. 



DIGESTIBILITY OF SOME BY-PRODUCT OILS. 



13 



Data of digestion experiments\ with pumpkin-seed oil in a simple mixed diet. 



Experiment, subject, and diet. 



Weight 
of food. 



Constituents of foods. 



Water. 



Protein. 



Fat. 



Carbo- 
hydrate. 



Ash. 



Experiment No. 829, subject P. K.: 

Blancmange containing pumpkin-seed oil 

Wheat biscuit 

Fruit 

Sugar 



Grams. 

1,429.0 
368.0 
318.0 
236.0 



Grams. 

723.2 

33.1 

276.3 



Grams. 

25.1 

39.0 

2.6 



Total food consumed. 
Feces 



2,351.0 
61.0 



1, 032. 6 



Amount utilized 

Digestibility of entire ration (per cent) . . 

Estimated digestibility of oil alone (per 

cent) 



Experiment No. 830, subject G. S. M.: 

Blancmange containing pumpkin-seed oil 

Wheat biscuit 

Fruit 

Sugar 



1,524.0 
231.0 
632.0 
445.0 



771.3 

20.8 

549.2 



Total food consumed. 
Feces 



2, 832. 
91.0 



1,341.3 



Amount utilized 

Digestibility of entire ration (per cent). . 
Estimated digestibility of oil alone (per 

cent) 

Average food consumed per subject per day . 



863.8 



395.7 



Grams. 

216.4 

5.5 

.6 



Grams. 

456.4 

284.5 

36.9 

236.0 



66.7 
18.2 



222.5 
11.1 



1, 013. 8 
26.6 



48.5 
72.7 



211.4 
95.0 

97.6 



987.2 
97.4 



26.8 

24.5 

5.0 



230.7 
3.5 
1.3 



486.8 

178.5 

73.3 

445.0 



56.3 
26.6 



235.5 
11.9 



1, 183. 6 
43.2 



29.7 
52.8 



223.6 
94.9 



1, 140. 4 
96.4 



20.5 



76, 



366.2 



Grams. 
7.9 
5.9 
1.6 



15.4 
5.1 



10.3 
66.8 



8.4 
3.7 
3.2 



15.3 
9.3 



6.0 
39.2 



5.1 



Summary of digestion experiments with pumpkin-seed oil in a simple mixed 

diet. * 





Subject. 


Digestibility of entire ration. 


Estimated 
digesti- 


Experiment No. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


bility of 
pumpkin- 
seed oil 
alone. 


829 


P. K 


Per cent. 
72.7 
52.8 


Per cent. 
95.0 
94.9 


Per cent. 
97.4 
96.4 


Per cent. 
66.8 
39.2 


Per cent. 
97.6 


830 


G. S.M 


98.7 








Average 


62.8 


95.0 


96.9 


53.0 


98.2 









In the two tests reported above the subjects ate 21 grams of pro- 
tein, 77 grams of fat, and 366 grams of carbohydrate, which sup- 
plied 2,235 calories of energy. Of the 76 grams of fat eaten daily 
74.5 grams was pumpkin-seed oil. As they reported no laxative 
effects resulting from this diet it may be concluded that the limit of 
tolerance for pumpkin-seed oil is in excess of 75 grams daily. The 
diet as a whole was well assimilated, for the digestibility was found 
to be 62.8 per cent for protein, 95 per cent for fat, and 96.9 per cent 
for carbohydrate. The value 98.2 per cent for the digestibility of 
pumpkin-seed oil implies that this oil is well assimilated. While 
the supply of pumpkin-seed oil available was sufficient for only two 
tests, the results of these seem to justify the conclusion that pumpkin- 
seed oil of good quality would be a valuable food and possess a dietary 
value similar to that of better-known edible oils. 



14 



BULLETIN 781, U. S. DEPARTMENT OF AGRICULTURE. 



TOMATO-SEED OIL. 



While definite figures regarding the amount of tomato seed result- 
ing from the commercial manufacture of tomato pulp and catsup 
are not available, it has been estimated by Eabak 1 that approximately 
1,500 tons of dry tomato seeds could be obtained annually. Dried 
tomato seeds contain approximately the same proportion of fixed oil 
as such well-known oil seeds as cotton seed, soy beans, etc. Tomato- 
seed oil may be obtained by either extracting or pressing the tomato 
seeds. When the seeds are subjected to the action of such solvents 
as ether or carbon tetrachlorid, a pale greenish-yellow oil is extracted. 
Expressed tomato-seed oil is of higher quality and usually requires 
less refining, but a smaller yield is obtained. 

From a study of the physical and chemical characteristics of 
tomato-seed oil as compared with those of cottonseed, soy bean, 
sesame, and corn oils, it appeared to Rabak 1 that tomato-seed oil 
should be equally useful and applicable to the same purposes as 
better-known oils of commerce. Accordingly, digestion experiments 
were here conducted to determine the digestibility of a well-refined 
tomato-seed oil prepared in the Bureau of Plant Industry labora- 
tories. 

This oil, which was of a brownish-yellow color, possessed a slight 
but quite distinctive odor arfd flavor. Both the odor and flavor were 
very completely masked when the oil was incorporated in the usual 
cornstarch blancmange. 

The results which were obtained in the three tests that were made 
of tomato-seed oil are recorded in the tables which follow : 

Data of digestion experiments with tomato-seed oil in a simple mixed diet. 

m 



Experiment, subject, and diet. 



Experiment No. 60S, subject I\ K.: 

Blancmange containing tomato-seed oil. . 

Wheat biscuit 

Fruit 

Sugar 



Total food consumed. 
Feces 



Amount utilized 

Digestibility of entire ration (per cent).. 
Estimated digestibility of oil alone (per 

cent) 



Experiment No. 609, subject J. C. M.: 

Blancmange containing tomato-seed oil. 

Wheat biscuit 

Fruit 

Sugar 



Total food consumed . 
Feces 



Amount utilized. 



Weight 
of food. 



Grams. 

2,142.0 
359.0 
692.0 
143.0 



3,336.0 
79.0 



Constituents of foods. 



Water. 



Grams. 

1,110.4 

32.3 

601.3 



1,744.0 



1,505.0 

306. 

1,030.0 

103.0 



2,944.0 
91.0 



780.2 

27.5 

895.1 



1,702.8 



Protein. 



Grams. 

38.8 

38.1 

5.5 



82.4 
26.1 



56.3 
68.3 



27.2 

32.4 

8.2 



67.8 
28.9 



Fat. 



Grams. 

194.7 

5.4 

1.4 



201.5 
20.9 



180.6 
88.1 

93. 3 



136.8 
4.6 
2.1 



143. 5 
12.4 



3S.9 
i U. S. Dept. Agr. Bui. 632 (1917), pp. 15. 



131- 1 



Carbo- 
hydrate. 



Grams. 

704.3 

277.5 

80.3 

143.0 



1,205-1 
23.3 



,181-8 
98.1 



494.9 
236.5 
119.5 
103.0 



953.9 
41.0 



912.9 



Ash. 



Grams. 

93.8 

5.7 

3.5 



103.0 

8.7 



94.3 
91.6 



65.9 
5.0 
5.1 



76.0 
8.7 



67.3 



DIGESTIBILITY OF SOME BY-PRODUCT OILS. 15 

Data of digestion experiments with tomato-seed oil in a simple mixed diet — Con. 



> 


Weight 
of food. 


Constituents of foods. 


Experiment, subject, and diet. 


Water. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


Experiment No. 609, subject J. C. M.— Con. 
Digestibility of entire ration (per cent).. 


Grams. 


Grams. 


Grams. 
57.4 


Grams. 
91.4 

97.5 


Grams. 
95.7 


Grams. 
88.6 


Estimated digestibility of oil alone (per 




















Experiment No. 610, subject C. T. W.: 

Blancmange containing tomato-seed oil. . 
Wheat biscuit 


1,960.0 

469.0 

746.0 

45.0 


1,016.1 

42.2 

648.3 


35.5 

49.7 

6.0 


178.2 
7.0 
1.5 


644.4 

362.6 

86.5 

45.0 


85.8 
7.5 


Fruit 


3.7 


Sugar 














Total food consumed 


3,220.0 
103.0 


1,706.6 


91.2 
32.1 


186.7 
16.3 


1,138.5 
45.8 


97.0 


Feces 


8.8 








Amount utilized 






59.1 
64.8 


170.4 
91.3 

96.6 


1,092.7 
• 96.0 


88.2 


Digestibility of entire ration (per cent) . . 






90.9 


Estimated digestibility of oil alone (per 




















Average food consumed per subject per day. . 


1,055.6 


572.6 


26.8 


59-1 


366.4 


30.7 



Summary of digestion experiments with tomato-seed oil in a simple mixed diet. 





Subject. 


Digestibility of entire ration. 


Estimated 
digesti- 


Experiment No. 


Protein. 


Fat. 


Carbo- 
hydrate. 


Ash. 


bility of 
tomato- 
seed oil 
alone. 


608 


P.K 


Per cent. 
68.3 
57.4 
64.8 


Per cent. 
88-1 
91.4 
91.3 


Per cent. 
98.1 
95.7 
96.0 


Per cent. 
91.6 
88.6 
90.9 


Per cent. 
93.3 


609 


J. C. M 


97.5 


610 


C. J. W 


96-6 








Average. 


63.5 


90.3 


96.6 


90.4 


95-8 









In the tests with tomato-seed oil the digestibility of the diet as a 
whole was found to be 63.5 per cent for protein, 90.3 per cent for fat, 
and 96.6 per cent for carbohydrate. On an average, the subjects ate 
27 grams of protein, 59 grams of fat, and 366 grams of carbohydrate, 
the energy value of which was 2,100 calories. The subjects ate ap- 
proximately 57 grams of tomato-seed oil daily. In one instance, Ex- 
periment No. 608, subject P. K., an average of over 67 grams of fat 
or approximately 65 grams of tomato-seed oil was eaten daily. In all 
of the tests the subjects reported that they were in normal physical 
condition and so it may be assumed that tomato-seed oil is fairly well 
tolerated by the human body. 

DISCUSSION. 

The table beyond summarizes the results of the digestion experi- 
ments with oils expressed from apricot, cherry, and peach kernels, 
and from melon, pumpkin and tomato seeds. The figures reported 



16 



BULLETIN 781, TJ. S. DEPARTMENT OF AGRICULTURE. 



for the digestibility of the protein, fat, and carbohydrate of the en- 
tire ration and those reported for the digestibility of the oil alone 
are obtained by averaging the results of the individual tests with 
the different oils. 

Summary of digestion experiments icith by-products oils. 



Kind of oil. 





Digestibility of entire ration. 


Average 


Number 
of experi- 
ments. 






amount 

of oil 

eaten per 

man per 

day. 


Protein. 


Fat. 


Carbo- 
hydrate. 




Per cent. 


Per cent. 


Per cent. 


Grams. 


4 


53.3 


94.4 


96.4 


68 


4 


79.9 


94.3 


97.6 


57 


3 


72.2 


94.8 


97.7 


40 


3 


83.7 


91.8 


95.6 


60 


2 


62.8 


95.0 


96.9 


75 


3 


63.5 


90.3 


96.6 


57 



Digesti 
bility 
of oil 
alone. 



Apricot-kernel oil 
Cherry-kernel oil . 

Melon-seed oil 

Peach-kernel oil. . 
Pumpkin-seed oil 
Tomato-seed oil . . 



Per cent. 
98.4 
98.0 
98.2 
96.6 
98.2 
95-8 



The amount of oil consumed in the above experiments was not as 
large as in the early experiments of this series, but, as noted on 
page 4, this was due to an inadequate supply of the oils under con- 
sideration and not to the quality of the oil. The small supply of oils 
also limited the number of experiments which could be made. 

No attempt was made to determine the upper limit of tolerance of 
these oils, but since in these tests as much as approximately 80 grams 
of apricot-kernel oil, 74 grams of cherry-kernel oil, 43 grams of melon 
(cantaloup) seed oil, 73 grams of peach -kernel oil, 77 grams of 
pumpkin-seed oil, and 65 grams of tomato-seed oil was eaten b} T one 
of the subjects for three successive days without physiological dis- 
turbances being noted, it is safe to conclude that the limit of toler- 
ance is in excess of these amounts. 

The coefficients of digestibility of the by-products oils, 98.4 per 
cent for apricot-kernel oil, 98 per cent for cherry-kernel oil, 98.2 per 
cent for melon (cantaloup) seed oil, 96.6 per cent for peach-kernel 
oil, 98.2 per cent for pumpkin-seed oil, and 95.8 per cent for tomato- 
seed oil indicates that these oils are very well assimilated by the 
body and possess a nutritive value equal to that of other better 
known edible oils, such as cottonseed, com, peanut, coconut, soy- 
bean, and olive oils. In general the experiments here reported indi- 
cate that as far as tolerance and assimilation are concerned apricot, 
cherry, and peach kernel, and melon (cantaloup), pumpkin, and 
tomato-seed oils, which at present are practically unutilized, are 
wholesome, nutritious foods, and should prove satisfactory for edible 
purposes. 



o 



LIBRARY OF CONGRESS 




LIBRARY OF CONGRESS 



012 822 384 8 




LIBRARY OF CONGRESS 



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